For a long time in our nation’s history, buildings were primarily framed with and often clad with wood harvested from the trees found in once plentiful forests. Except for a brief renaissance during the Craftsman era, as the country prospered, building aesthetics moved away from exposed timber. But, as I noted in a recent article for the Xpera blog called Tall Wood: The New Steel and Concrete, the trend seems to be shifting again, especially in the nonresidential and multi-family market.
When it comes to modern high-rise structures, however, concrete, steel and glass have long dominated. That may be starting to change. The move towards more sustainably sourced materials and practices is leading to a renewed interest in wood.
People not heavily involved in green building are often surprised to learn that wood is often a much more sustainable building material than steel. This is because wood is more readily renewable than concrete and steel. Sustainably sourced wood not only requires much less energy to produce, but it actually captures carbon from the atmosphere, thereby creating a positive impact on the environment
There’s a whole new generation of engineered wood products that take advantage of rapidly renewable wood, and in some cases, post-consumer recycled wood. When used in conjunction with adhesives, binders and other elements, they are able to produce very strong structural components. In some cases, these structural components have been proven to be as effective as steel reinforced concrete in resisting the types of forces necessary for high-rise buildings. These proprietary products go under a variety of names, such as cross laminated timber (CLT), glue-laminated timber (glulam), Parallam®, etc.
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The shift towards more sustainably sourced engineered wood products seems to be a positive change — so long as architects, engineers and contractors remain mindful of the potential risks. Case in point: The LEED Platinum Case Study Nobody Wants You To Read.
At the time it was built, the Chesapeake Bay Foundation’s Merrill Center was considered to be one of the greenest buildings in the world. But miscommunication and misunderstandings over compatibility of engineered wood products and waterproofing materials allowed for significant water intrusion, which then drastically impacted the structural integrity of those engineered wood products. In its lawsuit against the engineered wood manufacturer, the foundation claimed that “the structural integrity of the Project is in jeopardy and the building is now at risk of collapse. Thus, the defective condition of the PolyClear 2000 has created a clear risk of death or serious injury at the project.”
AEC Forensics 